1. Field of the Invention
The present invention relates to techniques for accessing digital content. More specifically, the present invention relates to a method and an apparatus for issuing rights in a digital rights management system.
2. Related Art
Most of today's commercial Digital Rights Management (DRM) systems and Conditional Access Solutions (CAS) support flexible content-usage models by delivering a license to a client with express usage rights. However, this technique has significant problems. Since the license with the express rights is stored along with the content, accidental destruction of the content typically destroys the license along with the content. For example, if a consumer purchases the rights to watch a movie on a portable media player, and the player is accidentally dropped into a swimming pool, thus ruining the device, then both the content and the license are probably ruined along with the device. In such cases, it can be very difficult for the consumer to obtain both a new copy of the license and the content to enable the user to view the movie on a new media player without repurchasing the license.
Furthermore, existing DRM systems typically do not work well in situations where the rights for a specific user to access an item of content are revoked. Since the license is typically stored with the content, once the user has the license, the user does not need to contact the license service again. If the license is subsequently revoked, as long as the user does not update the license with the license service, the user can continue to access the item of content.
Existing DRM systems also do not work well with “impulse buying” systems in limited-connectivity environments. For example, if a user is on an airplane and wants to listen to a song or watch a movie that exists on the user's media player, but the user does not currently have a license to access the song or movie, the user is typically denied access to the song or movie, and the user typically does not have a means to purchase a license because of the limited connectivity.
Hence, what is needed is a method and an apparatus for implementing a DRM system without the problems listed above.